Structural and non-structural components and assemblies (“elements”) are utilized in a variety of applications including, but not limited to, commercial, automotive and aircraft/aerospace. In many such applications, especially aircraft/aerospace, it may be useful for the elements to have high strength-to-weight ratios. After all, reducing the weight of the aircraft (while providing the required structural support/strength) may increase aircraft performance and reduce operating costs (since for example, less weight results in the use of less fuel, which in turn results in less operating costs). In aircraft applications, structural elements may be characterized as primary critical elements (i.e. those which provide a structural foundation or a safety mechanism) or non-critical elements (which provide structural support that are not critical for a structural foundation or a safety mechanism). Critical and non-critical structural elements, for example, are designed to accommodate certain load conditions and boundaries in order for the element to withstand the environment of usage by providing minimum structural support requirements, for instance.
Primary critical and non-critical structural elements utilized throughout a passenger aircraft have typically been manufactured from metal, and more particularly, aluminum alloy or other similar metals due to their inherent high strength-to-weight ratio. Use of such high strength-to-weight ratio metals, however, may be quite costly. For example, fabrication of such metal elements typically might require extensive machining, which may be time and labor intensive. Thus, such metal elements may not be compatible with low-cost, high volume manufacturing methodologies.
More recently, fiber reinforced resin molding has been used as an alternative to metal for forming non-critical elements having high strength-to-weight ratios. For such fiber reinforced resin molded elements (in which reinforcing fibers are dispersed throughout the resin, which is then molded into an element), consistency of strength depends on consistent fiber distribution. Unfortunately, this type of manufacturing process often results in inherent anomalies (which typically might result in weak spots in the element), which may include inconsistent distribution and dispersion of the fibers throughout the resin matrix due to inconsistent flow characteristics of the resin matrix, for example. Anomalies may especially be problematic when the final element is designed to include one or more apertures (which may be located in a structural or mechanical load zone or boundary, for example). The presence of an aperture may alter resin flow during formation, which may result in a knit or meld line (see FIG. 1 for example). Such knit or meld lines may cause significant strength reduction. Additionally, these types of anomalies (and the variations in the processing that typically might result in such anomalies) reduce the consistency/repeatability of manufacturing an element which meets specific structural requirements. This may require more frequent inspection and validation, including destructive mechanical validation, and thus may not be compatible with low-cost, high volume manufacturing methodologies.
If a manufacturing process is consistent and repeatable, on the other hand, and a test specimen meets dimensional and structural or mechanical performance inspection and validation, typical element acceptance might instead occur more efficiently using First Article Inspection procedures. This may aid in meeting low-cost, high volume manufacturing methodologies, for example. Accordingly, Applicants have developed embodiments including alternative manufacturing methods and elements, which may be more compatible with low-cost, high volume manufacturing methodologies.